1. Field of the Invention
The present invention is directed to a method and apparatus for classifying an atheroma, and in particular to such a method and apparatus on the basis of magnetic resonance imaging.
2. Description of the Prior Art
Arteriosclerosis is a general term meaning a decrease in the natural elasticity of the wall of an artery. Such a decrease in elasticity can occur as a result of various pathological sources, one of which is the build-up of an atheroma, commonly referred to as a deposit or plaque, on or within the interior surface of the artery wall. Arteriosclerosis due to the presence of an atheroma is referred to atherosclerosis.
In addition to producing a health risk due to reduced to cardiovascular efficiency, blockage or partial blockage of an artery, or any blood vessel, has the potential to cause the occurrence of a stroke. A stroke occurs when any of the significant vessels in the brain becomes sufficiently blocked so that oxygen deprivation in a region of the brain occurs. A frequent cause of stroke is that some or all of an atheroma becomes dislodged, and is carried by the natural blood flow to one of the vessels feeding the brain, where it creates a blockage resulting in the aforementioned oxygen deprivation.
It is known that different types of deposits or plaque in the blood vessels have different tendencies to become dislodged, and therefore certain types of deposits or plaque are more likely to create a risk of stroke than other types. It is known that plaque formed by calcifications and fibrous tissue, such as connective tissue and scar tissue, is less likely to become dislodged from the vessel wall than plaque formed by lipids. Currently, however, there is no imaging technique which allows these different types of plaques to be classified so that the risk or potential for dislodgement, and thus a stroke, can be assessed.